This presentation at the 2019 International Lewy Body Dementia Conference by Dr. David Irwin of the University of Pennsylvania offered a thorough overview of biomarkers. He started out with this "pre-test."
A biomarker is:
a) Paper and pencil cognitive test
c) Blood test
d) Spinal fluid test
d) Physical exam finding
f) Sleep study- Electrophysiology
g) ALL OF THE ABOVE
Yes, the answer is "All of the above." In the past, I had thought biomarkers were mainly those expensive and involved imaging tests that physicians use improve their diagnosis things like dementia. And they are that. But it turns out that many of the things we've experienced in doctor's offices and hospitals for years can be defined as "biomarkers."
According to the National Institute of Health, a biomarker is "a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes or a pharmacologic response to a therapeutic intervention."
More simply, a biomarker is anything that can be used to objectively measure an aspect of one's health or a response to treatment.
Biomarkers are used in two ways. The first is to assist in diagnosis (measure an aspect of one's health) The second is to track the progress of (a response to) an illness or its treatment.
Blood pressure is a biomarker we've used for centuries measure and track the health of our heart and circulatory system. Doctors can also use it to track the body's response to various drugs, such as those for high blood pressure. In the same way, the blood tests used to diagnose certain cancers can be used to track the body's response to treatment later.
With DLB, the type of LBD that starts before motor symptoms are evident, biomarkers are used diagnostically and as trackers. Diagnostically, they can facilitate an earlier diagnosis. The hope is that eventually, we will be able to use biomarkers to find Lewy bodies so early that they can be eliminated before they spread. They also help the diagnosing doctor differentiate DLB from the different dementias. Biomarkers can even firm up a choice of DLB vs. Parkinson's with dementia, the "other" LBD. As trackers, they help the doctor track progression and decide upon the best treatment.
The three most used DLB biomarkers are DAT (dopamine transport) imaging, I-MIBG scanning of the heart, and sleep studies. DAT measures the movement of a protein used to move dopamine in and out of a cell. Less activity means that DLB is more likely. I-MIBG is a radio-active tracer used to measure damage to the nerves that control automatic heart function. This damage can signal the presence of LBD. Sleep studies are used to identify the presence of REM sleep behavior disorder, or active dreams.
Another biomarker that you might come into contact is a short questionnaire that a primary doctor--or even care partners!--may use to identify the presence of enough LBD symptoms that a referral to a specialist is appropriate. This may or may not include the "clock test," where a hand drawn clock is used to judge concept and hand-eye coordination.
Naturally, biomarkers are also used with Alzheimer's disease (AD). There is more and more effort on identifying AD prior to symptoms. This will likely happen before it does with LBD, but many of the same techniques can be used for other neuro-diseases such as LBD, once they have succeeded with AD.
We aren't through talking about what happened at the LBD Conference yet! Next week, we will tell you about the LBDA's Research Centers of Excellence and what they can do for you.
For more information about Lewy body disorders, read our books:
A Caregivers’ Guide to Lewy Body Dementia
Managing Cognitive Issues in Parkinson's and Lewy Body Dementia
Responsive Dementia Care: Fewer Behaviors Fewer Drugs
Riding A Roller Coaster with Lewy Body Dementia: A Manual for Staff
Helen and James Whitworth are not doctors, lawyers or social workers. As informed caregivers, they share the information here for educational purposes only. It should never be used instead of a professional's advice.